For the production of the resonance \(X(6900)\)  in \(s\) -channel of \(\bar{p}p\rightarrow \psi \psi \)  reaction, the cross section can be calculated by
the standard Breit-Wigner formula [1]}.
\(\mathcal {\sigma }_{X}=\frac{2J+1}{(2S_{1}+1)(2S_{2}+1)}\frac{4\pi }{k_{in}^{2}}\frac{\Gamma ^{2}}{4}[\frac{Br(X\rightarrow \bar{p}p)Br(X\rightarrow \psi \psi )}{(W-W_{0})^{2}+\Gamma ^{2}/4}],\) 
